Diagram Maker – Free Online Diagram Tools & Templates
Build flowcharts, UML, ERD, network diagrams, mind maps, and block diagrams with the tools below. Choose drag-and-drop editors, template libraries, AI generators, or diagrams-as-code.
Export Your Diagram, Then Optimize for Web
Diagrams often export as heavy PNG/PDF files. Use ImageConver to resize, crop, compress, and convert (PNG ⇄ JPG ⇄ WebP) so pages load fast and text stays readable.
Editor’s Top Picks
diagrams.net (draw.io) – Free Diagram Maker
A go-to free diagram editor for flowcharts, UML, ERD, and network diagrams. Great exports (PNG/SVG/PDF).
Lucidchart – Diagram Maker
Strong template gallery and collaboration for teams building flowcharts, systems, and technical diagrams.
Canva – Diagram Maker
Quick, polished diagrams with templates—great for classroom visuals, presentations, and web graphics.
Diagram Maker Directory
Filter by: Free · Online · Templates · AI · Code · Enterprisediagrams.net (draw.io) – Online Diagram Maker
Free editor for flowcharts, UML, ERD, BPMN, org charts, and more.
Lucidchart – Diagram Maker
Collaborative diagramming with templates and integrations for teams.
Canva – Diagram Maker
Design-friendly diagrams for web, slides, and classroom visuals.
Miro – Diagram Maker (Diagramming)
Whiteboard-style diagramming for teams: from brainstorming to documentation.
Miro – Diagram Templates Collection
Browse ready-made diagram templates for common workflows and visuals.
Creately – Diagramming Platform
Visual workspace for diagrams plus collaboration and documentation.
FigJam – Diagram Tool (Figma)
Great for collaborative workshops, sticky notes, and quick diagrams.
Visual Paradigm Online – Free Diagram Maker
Online editor with templates and connectors for fast diagramming.
EdrawMax – AI Diagram Generator
Generate diagrams from text prompts, then refine and export.
SmartDraw – Block Diagram Maker
Template-driven diagramming for business and engineering-style visuals.
Excalidraw – Sketch-Style Diagrams
Hand-drawn look for quick diagrams, UX flows, and brainstorming.
Whimsical – Flowchart Maker
Fast flowcharts with a clean interface plus optional AI generation.
Mermaid Live – Diagrams as Code
Write Mermaid syntax and export diagrams for docs and wikis.
PlantText – PlantUML Editor
Generate UML diagrams from text (class, sequence, activity, state).
Google Drawings
Simple diagramming inside Google Workspace for quick charts and layouts.
Microsoft Visio
Popular diagramming option for organizations using Microsoft 365.
Miro – PlantUML Online Editor
Create diagrams from PlantUML text and import into Miro boards.
Mermaid Chart – Online Editor
Create Mermaid diagrams online with editing and export options.
Tip: For text-heavy diagrams, prefer SVG exports when available. For printing, use PDF. For websites, consider converting PNG → WebP after export.
Quick Compare: Which Diagram Maker Should You Use?
| Need | Best Choice | Why | Export Tip |
|---|---|---|---|
| Free, powerful diagram editor | diagrams.net | Great for flowcharts/UML/ERD with strong exports | Export SVG for crisp text |
| Team collaboration | Miro / Lucidchart | Co-editing, comments, and team workflows | Export PDF for sharing |
| Beautiful web graphics | Canva | Templates + design polish | Export PNG → convert to WebP |
| AI “text → diagram” | EdrawMax AI / Whimsical AI | Fast drafts from prompts | Review before publishing |
| Docs + version control | Mermaid / PlantUML | Diagrams as code (easy to diff + update) | Render to SVG for wikis |
Popular Diagram Types
- Flowchart: visualize steps, decisions, and processes
- Swimlane flowchart: show ownership across teams/roles
- UML: class, sequence, activity, use case diagrams
- ERD: database entities and relationships
- Network diagram: infrastructure and connections
- Block diagram: high-level system components
- Mind map: brainstorming and idea organization
Optimize Diagram Exports with ImageConver
- Export at the size you actually need (avoid huge canvases).
- Prefer SVG for crisp text; otherwise export PNG.
- Convert PNG → WebP for faster loading (when transparency isn’t needed).
- Compress gently and preview at 100% zoom before publishing.
Use ImageConver to compress, convert, and resize exports quickly.
Diagram Maker FAQ
SVG vs PNG: which is better for diagrams?
SVG is usually best for diagrams with lots of text because it stays sharp at any size. PNG is more universal when SVG export isn’t available. For print, use PDF.
How do I make a diagram mobile-friendly?
Keep labels short, increase font size, and consider exporting a “mobile crop” (split wide diagrams into sections). If you embed an SVG, ensure it scales responsively.
Can I use these tools commercially?
Many tools allow commercial use but may restrict certain templates or assets. Always check the licensing terms on the source website, especially for template libraries.
List last reviewed: Feb 27, 2026.